In their article on anticoagulant prophylaxis to prevent symptomatic venous thromboembolism (VTE) in hospitalized medical patients, Dentali and colleagues (1) base their conclusion that anticoagulant prophylaxis is effective on 2 overlapping significant findings, namely reductions in any pulmonary embolisms (PEs) and fatal PEs. These 2 differences were largely driven by the results of 3 studies: Cohen and colleagues' study (2), Gårdlund's study (3), and Mahé and colleagues' study (4). The devil is in the details, and closer examination of these data calls Dentali and colleagues' conclusion into question.

First, Cohen and coworkers report no PEs in the fondaparinux group and 5 “fatal PEs” in the control group at 15 days, but as the authors state: “Two of the five were confirmed by autopsy, the others were assumed to be due to pulmonary emboli, as no other plausible cause was found” (2). Because Dentali and colleagues state that they “only considered objectively documented and independently adjudicated outcomes,” the 3 “assumed” PEs should clearly not have been counted.